To keep up to the strict upcoming requirements of the emission legislation the combustion engine needs to be continuously improved and at the same time must not compromise on the costs of the Engine Control Unit (ECU). The Engine Management System (EMS) is challenged with an increasing number of injections and combustion modes thereby increasing the cost and size of the ECU's memory and its computation time. A combustion mode can be described as a set of combustion parameters that can be controlled by the software. Typically for a DS EU 4 application the combustion parameters controlled by the software are: injected fuel mass, injection position, rail pressure, air mass flow, boot pressure and EGR rate. The EMS needs to manage more combustion parameters that requires to be tuned for every combustion mode. During the past years there was a dramatic increase in the number of engine management control modes that are applied in specific conditions. The best known example for this is the Diesel particle filter (DPF) strategy that activates the filter regeneration every few hundred kilometers.
An other disadvantage in an EMS with an increasing number of combustion modes is the fast-growing ROM consumption due to the high number of calibration maps. This happens because the calibration engineers need to calibrate all the combustion parameters at each working point for each combustion mode in order to reach the relevant target such as consumption, noise, emissions, etc.
Such a typical know EMS architecture is shown in FIG. 1. The increasing number of the combustion modes lead to the following problems. First of all only one combustion mode can be executed at a time. Therefore if two or more combustion modes are requested a decision needs to be taken. In order to solve conflict between combustion modes prioritization has been implemented at different levels in the software. Every time a new mode manager is introduced possibly all other mode managers such as DPF manager or RTE manager in FIG. 1 need to be modified thus causing unclear and spread decision algorithm for mode prioritization. Additionally the transition between the combustion modes has to be handled in a torque neutral way.
The simple approach of creating a calibration structure that allows the tuning of all combustion set-points and making a new copy of it for every new combustion mode is not feasible. The reason is that the required ROM resources for this would severely increase the ECU costs and in many cases it would force an upgrade to a better processor and additionally increasing costs.